Hall Effect water flow sensor

LOTTOWINNER

Intend using a hall effect water flow meter, 3 wires VCC GND and SIG OUT, the output pulse ranges between 100 and 200 Hz depending on the flow, measured on scope, nice clean square wave, amplitude depends of VCC.

I want something really simple (not interested in measuring rate) just want logic high when there's a flow and a logic low when there isn't.

I tried using a D type flip flop, but didn't succeed!!

So any suggestions would be great.

pulses

---

High
no pulses

---

Low

Thanks.

Johnboy1951

A simple analogue level switch fed with a diode and small cap ....... cap will discharge in the absence of the pulses.

LOTTOWINNER

Thanks Johnboy,

I'll give it a try tomorrow, I love simple solutions!! less things to go wrong.

DublinDilbert

You want a high pass filter as the first stage, a simple RC circuit can do this.

Pass the signal through the series capacitor (electrolytic 10uf at a guess) this will conduct the fundamental A/C component of the square wave. The put the output of the series cap into an RC filter. You might also need a resistor between the output of the series cap and ground.

I would imagine when the flow stops the output of the flow meter could be high or low, depending on where the flow meters stops. If the flow meter stops high the series cap will charge up and the output voltage goes to zero quickly.